Two piece magnetic swaging device

ABSTRACT

This invention relates to devices for coupling metallic tubes and in particular to a two piece magnetic swaging device having a split single turn winding in the form of a rectangular assembly with upper and lower symmetrical parts with semicylindrical recesses therein selectively joined to form the swaging device.. The upper and lower pieces each consists of a solid half-turn coil with an extension which overlaps the extension of the other piece to provide parallel current paths and reduced circuit inductance.

United States Patent [72] Inventor Harold P. Furth 55 Locust Lane,Princeton, Na]. 08540 [21] Appl. No. 807,476

[22] Filed Feb. 7, 1969 [45; Patented Aug. 311, 1971 l 54] W0 MAGNETICSWAGING DEVICE [52] US. Cl. 72/56, 72/706 [51] Int-Cl B211d 26/114- [50]Field of Search 72/56, 706; 29/421 [56] Reterences Cited UNITED STATESPATENTS 3,203,211 8/ 1965 Mallinckrodt 72/56 3,252,313 5/1966 Eilers eta1. 72/56 [111 dfid 3,347,074 10/1967 Eilers et a1. 72/56 3,383,8905/1968 Wildi 72/56 3,391,558 7/1968 Deeg 72/56 3,412,590 11/1968 Lippmanet a1 72/56 Primary Eraminer- Richard J Herbs! Attorney-John A. DuffyABSTRACT: This invention relates to devices for coupling metallic tubesand in particular to a two piece magnetic swaging device having a splitsingle turn winding in the form of a rectangular assembly with upper and1ower symmetrical parts with semicylindrical recesses thereinselectively joined to form the swaging device. The upper and lowerpieces each consists of a solid half-turn coil with an extension whichoverlaps the extension of the other piece to provide parallel currentpaths and reduced circuit inductance.

PATENTEU A1103: IS?! 3,602,023

sum 1 0F 3 INVENTOR #42010 I? FUK? TA! PATENTEU M1331 1811 8,602,023

SHEET 3 [IF 3 INVENTOR. H/IEOLO R FA/fiT/l TWO PIECE MAGNETIC SWAGINGDEVICE BACKGROUND OF THE INVENTION The swaging of metallic tubes bymagnetic forming is accomplished by applying magnetic pressure to theend portions of the tubes to be joined. A high amperage current isapplied to a forming coil surrounding the tubes to generate a highintensity magnetic field which interacts with current in the skin of thetubes to generate the magnetic pressure. The large amount of pressureavailable from magnetic swaging produces a rigid and tight joint whichis vastly superior to the more common methods of coupling tubes.

In a copending application entitled Magnetic Swaging Device, in the nameof Ralph W. Waniek, there is described a magnetic swaging device inwhich the swaging coil consists of two structural pieces which can beclosed over metallic tubes to be joined and opened to be removed afterthe swaging operation. The massive single turn coil of two separableparts is especially adaptable in applications wherein tubes to be joinedare either long, have their ends structurally obstructed, or varyappreciably in cross section.

The device of the present invention represents a substantial improvementover the above described magnetic swaging configuration and is aimedparticularly at improving the efficiency of current conduction. In theabove described copending application a single turn winding in the formof a rectangular assembly has upper and lower symmetrical parts withsemicylindrical recesses therein joined to form the swaging device. Thetransition point between the parts has a high current overlap tab atright angles to the axis of the winding to reduce arcing during currentpassage. Nevertheless current problems such as arcing and increasedinductance occur due to mechanical imperfections in the structure. Themagnetic swaging device of the present invention reduces arcing andinductance by providing two parallel plates utilized as transmissionlines for directly coupling current from a source to the swaging coils.

OBJECTS OF THE INVENTION Accordingly it is an object of this inventionto provide a two piece magnetic swaging device of improved efficiency.

It is another object of this invention to provide a two piece magneticswaging device having a low inductance in the current supply coils.

It is a further object of this invention to provide a magnetic swagingdevice in which the current coils are two-piece coils of low inductance.

It is still another object of this invention to provide a magneticswaging device in which current is directly coupled from the energysource to the swaging coils.

SUMMARY OF THE INVENTION The magnetic swaging device of this inventionswages two tubes to be joined by magnetic forming. Two massive metallicstructures are shaped to be joined and to form one massive single turncurrent coil having a recess for receiving the metallic tubes to becoupled by swaging. Each of the pieces of the coil consists of a solidsemicircular shape having an extension which overlaps the extension ofthe other piece to provide a parallel current path. Each of the coils isstructurally joined to and forms a part of a massive plate transmissionline. The plates are completely overlapped to provide a low inductancecurrent path.

According to one embodiment of the invention the twopiece coil is formedto provide a circular recess for insertion of tubes to be swaged.According to another embodiment of the invention a pair of coils areshaped to provide an opening whose connection is adjustable by movingthe coil pieces vertically. In this manner the size of the cross sectionmay be varied according to the desired size and shape of the tubes to beswaged. According to still another embodiment of the invention thetwo-piece coil is formed of two coil pieces each having flexible leadsattheir ends which are spring loaded to provide a compact magnetic swagingdevice. In still another embodiment of the invention the coil pieces arestructured to be perpendicular to the flow of current through thecircular recesses.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a cross-sectional view of amagnetic swaging device of the invention illustrating an embodiment inwhich a pair of tubes are in place for swaging by magnetic forming.

FIG. 2 is a view of the device of FIG. 1 showing the twopiece coilbefore being put in place for forming.

FIG. 3 is a cross-sectional view of a magnetic swaging device of theinvention illustrating another embodiment in which the two piece coil isin the form of a pair of pear-shaped coils.

FIG. 4 is a cross-sectional view showing the coils of the device of FIG.5 and FIG. 5 is a cross-sectional view of another embodiment of theinvention in which the leads of the two-piece coils are flexiblyattached during operation.

FIG. 6 is an end view of the embodiment of the invention illustrated inFIG. 5.

FIGS. 7a and 7b are views of another embodiment of the invention inwhich the swaging assembly is arranged to swage tubes of extreme length.

FIGS. 8a and 8b illustrate an embodiment of the invention in which theswaging assembly is normal to the coils.

DETAILED DESCRIPTION OF A PARTICULAR EMBODIMENT Referring to thedrawings and in particular to FIG. I there is illustrated a magneticswaging device according to the invention in which a pair of metallictubes 11 and 12 are to be swaged. The tubes 11 and 12 may be obstructedsuch as being rigidly joined making it impractical to fit a multiturncoil around the tubes at the point to be swaged. A pair of massivesingle turn coils 13 and 14 are fitted together to provide a splitsingle turn structure having a cylindrical recess to encompass themetallic tubes 11 and 12. Each of the coils 13 and 14 is structurallyjoined to and forms a portion of a massive plate transmission line, 26for coil 13, and 27 for coil 14 which is connected optionally through acoupling transformer 18 to a source of energy (as shown in FIG. 5) suchasa capacitor bank through a switch. Thus the coils are directly coupledto the transformer 18 through the usual conductor leads. Each of thecoils I3 and I4 is constructed identically as shown in the view of FIG.2 with a suitable insulator separating the coils. The current paththrough the coils 13 and I4 is illustrated by arrows 26 for coil 13 and27 for coil 14. The current from a transformer (shown in FIG. 5) is fedseparately to each of the coils l3 and 14 or with the coils in series.

Each of the coils 13 and M has an extended portion of transmission line24, for coil 13, and 25 for coil 14, as seen in FIG. 2, which overlapsthe other extended portion of the other respective coil. The extendedportions 26 and 27 are suitably insulated by insulator 29 to providedoverlapping parallel plates.

Metallic tubes 11 and 12 are suitably placed in the fitting hole formedby semicircular openings of the coils I3 and 14. When the coils I3 and14 are fitted together under suitable pressure (not shown) a circularhole is formed to fit adjacent to the periphery of the tubes II and 112.The coils l3 and 14 are held together by suitable means for maintainingthem structurally joined even at a large pressure. In the cylindricalrecess formed by the coils 13 and 14 the tubes 11 and 12 are insulatedfrom the coils I3 and M by insulator 26. The coils l3 and 114 areinsulated from each other at the junction points by insulator 27.

Magnetic swaging of the tubes II and I2 is accomplished by thegeneration of magnetic pressure by the interaction of the magnetic fieldgenerated by the coils l3 and M on the skin of the tubes 1 l and 12 andthe current flowing in the tubes. Magnetic pressure is simultaneouslyapplied to the upper and lower halves of the tubes 11 and 12 by thesimultaneous application of high current pulses to the coils 13 and 14.

As current flows from the transformer into the coil pieces 13 and 14current paths are created through the extension pieces 24 and 25 whichare in parallel and thus provide a low inductance path to minimizecurrent losses. As seen by arrows 28 and 29 in FIG. 2, current in thecoils 13 and 14 flows in parallel at the extensions 26 and 27.

In another embodiment of the invention as shown in FIGS. 3 and 4 themassive single turn coil is achieved by two pole pieces 31 and 32 whichhave noncircular openings and adapted to fit over each other to form anaperture which is varied in cross section by the movement of the coils31 and 32 with respect to each other. The coil 31 is a massive singleturn coil and is connected to receive a high amp current pulse from thehigh current pulse transformer connected to a suitable energy sourcethrough a switch. The coil piece 32 is similarly shaped and connected toreceive a current pulse from a transformer in turn connected to acapacitor through a switch (as seen in FIG. The pieces 31 and 32 arecomplimentarily shaped so that when fitted over each other as shown inFIG. 4 they form a cylindrical recess which can be varied in size andshape to fit the tubes to be swaged. Movement of the coils 31 and 32 upand down allows the increase of the opening to fit tubes withprotrusions.

In the embodiment of FIGS. 3 and 4 current passes through the pieces 31and 32 along current paths which are in parallel as illustrated by thearrows 41 and 42 in FIG. 4.

FIGS. 5 and 6 illustrate an embodiment of the invention in which a pairof coil pieces 51 and 52 each has flexible leads which are undersuitable pressure (not shown) when the pieces 51 and 52 are in positionfor swaging.

Referring now to FIGS. 7a and 7b there is illustrated an embodiment ofthe invention in which the swaging coil lies in a surface which is at anangle with the transmission lines. In FIGS. 7a and 7b the coils 61 and61 are fed current from a source (not shown) through paralleltransmission line plates 64 and 65. Tubes 66 and '67, to be swaged, mayhave protrusions (not shown) which will not interfere with thetransmission line plates 64 and 65.

In FIGS. 80 and 8b the swaging coils 7l and 72 lie in a surface which isnormal to the surface of the transmission line plates 73 and 74. Thedevice of FIGS. 8a and 8b has the same advantage of the device of FIGS.70 and 7b, in addition to being more adaptable to fit the necessaryhardware for applying pressure to the coil during the swaging operation.

The illustrated magnetic swaging devices swage a pair of metallic tubes.It is to be realized that it is within the scope of the invention for adevice patterned after those illustrated in the drawings to swage anyshape metallic objects other than the cylindrical shapes illustrated.

While the invention has been disclosed herein with respect to theembodiments illustrated in the drawings, it will be readily apparentthat numerous variations and modifications may be made within the spiritand scope of the invention.

It is claimed:

1. In a magnetic swaging device,

a pair of semicircular coils arranged to fit side by side to form asingle current carrying swaging coil,

each said coil having an extended portion overlapping the extendedportion of the other said coil,

each said coil forming one-half of an assembly having upper and lowersymmetrical parts consisting of said coils with semicircular recessestherein,

said coils overlapping each other except in the region of said circularrecesses,

a pair of transmission lines structurally joined to respective coils,

a source of high current energy for each said transmission line saidcoils responsive to said sources of energy connected through saidtransmission lines for generating magnetic fields,

each said coil having a magnetic field penetrating said semicircularrecesses,

the current flowing through each said coil overlapping the currentflowing in the other said coil so as to provide a low impedance,

said circular recess adapted to receive a pair of metallic tubes to beswaged.

2. The magnetic swaging device recited in claim 1 wherein said coils arenoncircularly shaped to provide a circular aperture of variable crosssection as said coils are moved with respect to each other.

3. The magnetic swaging device recited in claim 1 wherein saidtransmission lines are in the form of parallel plates.

4. The magnetic swaging device recited in claim 1 wherein saidtransmission lines are in the form of parallel plates which are arrangedto completely overlap each other to provide extremely low impedance tothe flow of current.

5. The magnetic swaging device recited in claim 1 wherein saidtransmission lines are in a surface normal to the surface of said coils.

6. The magnetic swaging device recited in claim 1 wherein saidtransmission lines are in the form of parallel plates which lie in asurface parallel to the surface of said coils.

7. The magnetic swaging device recited in claim 1 wherein saidtransmission lines are in the form of parallel plates which lie in asurface at a predetermined angle to the surface of said coils to allownoninterference with said metallic tubes.

1. In a magnetic swaging device, a pair of semicircular coils arrangedto fit side by side to form a single current carrying swaging coil, eachsaid coil having an extended portion overlapping the extended portion ofthe other said coil, each said coil forming one-half of an assemblyhaving upper and lower symmetrical parts consisting of said coils withsemicircular recesses therein, said coils overlapping each other exceptin the region of said circular recesses, a pair of transmission linesstructurally joined to respective coils, a source of high current energyfor each said transmission line, said coils responsive to said sourcesof energy connected through said transmission lines for generatingmagnetic fields, each said coil having a magnetic field penetrating saidsemicircular recesses, the current flowing through each said coiloverlapping the current flowing in the other said coil so as to providea low impedance, said circular recess adapted to receive a pair ofmetallic tubes to be swaged.
 2. The magnetic swaging device recited inclaim 1 wherein said coils are noncircularly shaped to provide acircular aperture of variable cross section as said coils are moved withrespect to each other.
 3. The magnetic swaging device recited in claim 1wherein said transmission lines are in the form of parallel plates. 4.The magnetic swaging device recited in claim 1 wherein said transmissionlines are in the form of parallel plates which are arranged tocompletely overlap each other to provide extremely low impedance to theflow of current.
 5. The magnetic swaging device recited in claim 1wherein said transmission lines are in a surface normal to the surfaceof said coils.
 6. The magnetic swaging device recited in claim 1 whereinsaid transmission lines are in the form of parallel plates which lie ina surface parallel to the surface of said coils.
 7. The magnetic swagingdevice recited in claim 1 wherein said transmission lines are in theform of parallel plates which lie in a surface at a predetermined angleto the surface of said coils to allow noninterference with said metallictubes.